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1.
Adv Mater ; : e1907061, 2020 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-32022974

RESUMEN

Solar vapor generation has presented great potential for wastewater treatment and seawater desalination with high energy conversion and utilization efficiency. However, technology gaps still exist for achieving a fast evaporation rate and high quality of water combined with low-cost deployment to provide a sustainable solar-driven water purification system. In this study, a naturally abundant biomass, konjac glucomannan, together with simple-to-fabricate iron-based metal-organic framework-derived photothermal nanoparticles is introduced into the polyvinyl alcohol networks, building hybrid hydrogel evaporators in a cost-effective fashion ($14.9 m-2 of total materials cost). With advantageous features of adequate water transport, effective water activation, and anti-salt-fouling function, the hybrid hydrogel evaporators achieve a high evaporation rate under one sun (1 kW m-2 ) at 3.2 kg m-2 h-1 out of wastewater with wide degrees of acidity and alkalinity (pH 2-14) and high-salinity seawater (up to 330 g kg-1 ). More notably, heavy metal ions are removed effectively by forming hydrogen and chelating bonds with excess hydroxyl groups in the hydrogel. It is anticipated that this study offers new possibilities for a deployable, cost-effective solar water purification system with assured water quality, especially for economically stressed communities.

2.
Anal Chim Acta ; 1101: 176-183, 2020 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-32029109

RESUMEN

This research introduced a new low-cost and multi-parameter analyzer for in-situ measurements of typical nutrients in water bodies. The analyzer consisted of color detection and chromogenic reaction modules. The self-sampling action of the 3D printed sampling/reaction cells was achieved with the cooperative application of rubber bands and dissolvable thread. The target analytes in the collected water sample reacted with the chromogenic reagents that were diffused from the pre-placed glass wool in the cell, producing color compounds. A portable document scanner was employed as a multi-parameter in-situ detector to record the image of the colored solutions in all five cells simultaneously. Based on the image, the corrected grayscale values were derived for target analyte quantitation. The relationships between grayscale values and concentrations of target analytes were established, and the temperature effects were studied. In addition, the practicability of the analyzer was demonstrated by in-situ experiments carried out in four different sites, including a creek, a river dock, a reservoir and a secondary settling tank in a wastewater treatment facility. The results indicated that the analyzer could be used for in-situ measuring of nutrients at µmol/L levels in the water. The nutrient concentrations obtained with the analyzer were comparable with those obtained with the standard methods. The presented analyzer provided new complementary ideas and methods for in-situ rapid measurement of nutrients and other target analytes in various water systems.

3.
Sci Total Environ ; 711: 134644, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-32000319

RESUMEN

The present study describes the preparation of 50.3 nm superparamagnetic nanosorbents with high surface area for the adsorptive removal of lead and methyl orange from water. This material is based on the surface modification of iron oxide superparamagnetic nanoparticles with a double-shell coating of mesoporous silica whose porosity was increased up to 570 m2/g by the addition of a porogenic material and its calcination. The adsorptive performance of the nanosorbent was evaluated as a function of several parameters (e.g. solution pH, pollutant initial concentration, and contact time), concluding that pHs around 5 are needed to avoid precipitation of Pb2+ as Pb(OH)2 and the equilibrium adsorption capacity is reached after 2 h in all cases. The experimental data on the adsorption capacity of lead and methyl orange onto the nanosorbent were fit to a pseudo-second order kinetic model and Langmuir isotherm model. The maximum adsorption capacity value increases from 35 up to 50 mg/gNS for lead removal with increasing nanosorbent surface area. Contrary, for methyl orange the maximum adsorption goes up to 240 mg/gNS, indicating a larger nanosorbent surface affinity for the organic matter that is able to diffuse through the silica pores as probed by the intraparticle diffusion model. In addition, we found an good reusability (100% recovering after 4 sorption/desorption cycles for methyl orange removal), which makes of this magnetic nanosorbent suitable for remediation technologies.

4.
Water Res ; 172: 115471, 2020 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-32032913

RESUMEN

Lagoon has been widely used to treat animal wastewater. However, because lagoon effluent often fluctuates in water quality, land application of the effluent may pose a risk to the environment and/or public health. It is necessary to monitor the quality of lagoon water to reduce the risk of its land application. This paper proposes an innovative monitoring method for animal wastewater in lagoons. We implemented spectral processing techniques to analyze the reflectivity of wastewater samples from lagoons, and applied machine learning methods to estimate the water quality parameters of the effluents, including the levels of nitrogen, phosphorus, bacteria (total coliform and E. Coli), and total solids. This study found significant correlations between the spectral rate of emission and above water quality parameters. We used machine learning to train three types of estimators, normal equation linear regression (LR), stochastic gradient descent (SGD), and Ridge regression to quantify these relations. The model performance was evaluated by weight coefficient, function intercept, and mean squared error (MSE). The model showed that TS level and the blue band of spectral reflectance of samples have a relatively good linear relationship, and the MSE of prediction set and decision coefficient were 0.57 and 0.98, respectively. For bacteria level, the MSE of prediction set was 0.63, and coefficient R2 was 0.96. The results from this study could provide a versatile method for remote sensing of animal waste water.

5.
FEMS Microbiol Ecol ; 96(2)2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-31913449

RESUMEN

Spatial patterns of bacterial community composition often follow a distance-decay relationship in which community dissimilarity increases with geographic distance. Such a relationship has been commonly observed in natural environments, but less so in engineered environments. In this study, bacterial abundance and community composition in filter media samples (n = 57) from full-scale rapid biofilters at 14 water treatment facilities across North America were determined using quantitative polymerase chain reaction and Illumina HiSeq high-throughput sequencing targeting the 16S rRNA gene, respectively. Bacteria were abundant on the filter media (108.8±0.3 to 1010.7±0.2 16S rRNA gene copies/cm3 bed volume) and the bacterial communities were highly diverse (Shannon index: 5.3 ± 0.1 to 8.4 ± 0.0). Significant inter-filter variations in bacterial community composition were observed, with weighted UniFrac dissimilarity values following a weak but highly significant distance-decay relationship (z = 0.0057 ± 0.0006; P = 1.8 × 10-22). Approximately 50% of the variance in bacterial community composition was explained by the water quality parameters measured at the time of media sample collection (i.e. pH, temperature and dissolved organic carbon concentration). Overall, this study suggested that the microbiomes of biofilters are primarily shaped by geographic location and local water quality conditions but the influence of these factors on the microbiomes is tempered by filter design and operating conditions.

6.
Ecol Appl ; 2020 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-31965659

RESUMEN

The ecological literature reports little empirical evidence from biodiversity - ecosystem functioning (BEF) experiments in wetland systems, even though wetlands are widely known for their water filtering capacity. Experiments comparing the effect of plant monocultures and mixtures on water quality to improve pollutant removal efficiency in treatment wetlands share the characteristics of classical BEF experiments, and so could provide insights for wetland management. To add to our understanding of BEF relationships in wetlands, we evaluated plant diversity effects on water purification through a meta-analysis of freshwater experimental wetlands comparing monocultures to mixtures. We found 28 studies that matched our criteria for BEF analysis, for a total of 561 diversity effects on pollutant removal. Overall, the meta-analysis shows no significant effect of plant richness on removal of total suspended solids, but a positive effect on chemical oxygen demand and total nitrogen removal, and a marginal effect on phosphorus removal. Thus, the results of this meta-analysis are consistent with reports of an overall positive biodiversity effect on ecosystem properties. An analysis of moderator variables shows that the experimental context (size of the experimental units, nutrient load, duration of the experiment) does not explain much of the residual variance. For pollutants that benefit from a positive plant richness effects on removal, mixtures do not perform better than the best monoculture. We found no evidence that plant richness effects are due to functional complementarity among species rather than to the presence of particularly efficient species. Complementarity effects may be less prevalent in highly productive, nutrient-rich wetlands, compared to nutrient-limited environments such as natural grasslands. Although findings must be confirmed by long-term field experiments under natural conditions, result from experimental wetland systems may contribute to a better understanding of biodiversity effect on ecosystem functions in wetlands, in addition to guide practices in natural wetland restoration and the use of constructed wetlands for water treatment.

7.
Life Sci Space Res (Amst) ; 24: 64-82, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31987481

RESUMEN

Human missions to establish surface habitats on the Moon and Mars are planned in the coming decades. Extraplanetary surface habitat life support systems (LSS) will require new capabilities to withstand anticipated unique, harsh conditions. In order to provide safe, habitable environments for the crew, water purification systems that are robust and reliable must be in place. These water purification systems will be required to treat all sources of water in order to achieve the necessary levels of recovery needed to sustain life over the long-duration missions. Current water recovery and purification systems aboard the International Space Station (ISS) are only partially closed, requiring external inputs and resupply. Furthermore, organic wastes, such as fecal and food wastes, are currently discarded and not recycled. For long-duration missions and habitats, this is not a viable approach. The inability to recycle organic wastes represents a lost opportunity to recover critical elements (e.g., C, H, O, N, P) for subsequent food production, water purification, and atmospheric regeneration. On Earth, a variety of technologies are available to meet terrestrial wastewater treatment needs; however, these systems are rarely completely closed-loop, due to lack of economic drivers, legacy infrastructure, and the (perceived) abundance of resources on Earth. Extraplanetary LSS provides a game-changing opportunity to incentivize the development of completely closed-loop systems. Candidate technologies may be biological, physical, or chemical, with associated advantages and disadvantages. This paper presents a survey of potential technologies, along with their inputs, outputs and requirements, which may be suitable for next-generation regenerative water purification in space. With this information, particular technologies can be down-selected for subsystem integration testing and optimization. In order for future space colonies to have closed-loop systems which minimize consumable inputs and maximize recovery, strategic implementation of a variety of complementary subsystems is needed.

8.
J Environ Manage ; 258: 110039, 2020 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-31929073

RESUMEN

Water scarcity is a global issue that is threatening social and economic development. One approach to alleviating scarcity is the incorporation of new water sources into supply systems, including desalinated seawater for industrial and municipal use. In Chile, large volumes of water are used in water-scarce regions where mining takes place, alongside agriculture and small communities. This situation has driven a debate around policies to increase the use of seawater to satisfy the water demand of the mining industry. The economic, social and environmental implications of such a policy, however, are poorly understood and the current regulatory framework to address concerns and uncertainties is inadequate. This paper presents a technical, legal, economic and environmental appraisal of such a policy and considers options to improve outcomes. The appraisal suggests that clear regulations derived from economic, social and environmental analysis must be generated to provide legal certainty and reduce risks. Alternative or complementary water supply options should be allowed where mining operations can demonstrate negligible hydrological and social impacts or use innovative solutions such as stakeholder water rights swaps and water efficiency technologies. We provide insight that will help to drive a better policymaking process aimed at tackling water scarcity in Chile and in similar areas of the world.


Asunto(s)
Purificación del Agua , Agua , Chile , Política Pública , Abastecimiento de Agua
9.
J Environ Manage ; 256: 109964, 2020 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-31989983

RESUMEN

The contamination of water resources by nitrate is a global problem. Indeed, traditional treatment technologies are not able to remove this ion from water. Alternatively, biological denitrification is a useful technique for natural water nitrate removal. This study aimed to evaluate the use of glycerol as a carbon source for drinking water nitrate removal via denitrification in a reactor using microorganisms from natural biomass. The experiment was carried out in a continuous fixed bed reactor using immobilised microorganisms from the vegetal Phyllostachys aurea. The tests were started in batch mode to provide cells growth and further immobilisation on the support. Then, the treatment experiments were accomplished in an up-flow continuous reactor. Ethanol was used as the primary carbon source, and it was gradually replaced by glycerol. The C:N (carbon to nitrogen) ratio and the hydraulic residence time (HRT) were evaluated. It was possible to remove 98.14% of nitrate using a C:N ratio and HRT of 3:1 and 1.51 days, respectively. The results have demonstrated that glycerol is a potential carbon source for denitrification in a continuous reactor using immobilised cells from natural biomass.


Asunto(s)
Agua Potable , Purificación del Agua , Biomasa , Reactores Biológicos , Carbono , Desnitrificación , Glicerol , Nitratos , Nitrógeno
10.
Water Res ; 172: 115490, 2020 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-31972414

RESUMEN

Continuous high frequency water quality monitoring is becoming a critical task to support water management. Despite the advancements in sensor technologies, certain variables cannot be easily and/or economically monitored in-situ and in real time. In these cases, surrogate measures can be used to make estimations by means of data-driven models. In this work, variables that are commonly measured in-situ are used as surrogates to estimate the concentrations of nutrients in a rural catchment and in an urban one, making use of machine learning models, specifically Random Forests. The results are compared with those of linear modelling using the same number of surrogates, obtaining a reduction in the Root Mean Squared Error (RMSE) of up to 60.1%. The profit from including up to seven surrogate sensors was computed, concluding that adding more than 4 and 5 sensors in each of the catchments respectively was not worthy in terms of error improvement.

11.
Environ Technol ; 41(5): 658-668, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-30074861

RESUMEN

Monolayers of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane have been established on magnetite nanoparticles to develop a novel magnetic adsorbent for fast decontamination of hexavalent chromium (Cr(VI)) from water. Results indicated that monolayer adsorption of the silane from water took place at low concentrations (<300 mg/L) and around 100% surface coverage was obtained at temperatures ≥90°C. The hydrolysed silane was anchored to the magnetite surface through condensation reactions between its silanol groups and the surface hydroxyl groups of magnetite. The functional amine groups were protonated by acid treatment for adsorbing Cr(VI). The monolayer of the silane on magnetite (MSM) with approximately 100% surface coverage showed extremely rapid adsorption kinetics for Cr(VI), such that the process was complete within 1 min. This enables the treatment of large amounts of sewage per unit time. The adsorption capacity for Cr(VI) was 8.0 mg/g, as estimated from the Langmuir isotherm model. The saturation magnetization of the MSM reached 64.16 emu/g, allowing easy magnetic recovery from water. In the presence of up to 50-fold molar excesses of chloride and nitrate anions, little effect on Cr(VI) removal was seen, but moderate and large impacts were observed with sulphate and hydroxyl anions, respectively. Desorption of adsorbed Cr(VI) and regeneration of the MSM were successfully achieved by NaOH and HCl treatments to deprotonate and protonate the amine groups, respectively. By selecting a silane with suitable functional groups, the surface properties may be tailored for a particular pollutant.


Asunto(s)
Nanopartículas de Magnetita , Compuestos de Organosilicio , Minorías Sexuales y de Género , Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Cromo , Homosexualidad Masculina , Humanos , Concentración de Iones de Hidrógeno , Cinética , Masculino , Agua
12.
Water Res ; 170: 115323, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31790888

RESUMEN

In this work, we investigated the effect of bromide ion (Br-) on NDMA formation using model precursor compounds, wastewater effluents and surface waters. Previous studies showed that Br- reacts with chloramines and forms bromochloramine, a reactive compound responsible for NDMA formation enhancement. Some limitations of those studies were the highest Br- concentrations used, and the limited number of precursors considered. Here, we observed enhancement of NDMA formation from most of the model precursor compounds within the Br- range (0-1000 µg/L) but this effect was suppressed in the presence of NOM. Also, NDMA formation was favored at pH 8 in the presence of Br- compared to pH 6. Nevertheless, Br- suppressed NDMA formation in wastewater effluent samples at low monochloramine doses while no effects were observed in surface waters.


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Bromuros , Cloraminas , Dimetilnitrosamina , Aguas Residuales
13.
Water Res ; 170: 115334, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31794889

RESUMEN

Echinococcus multilocularis is a parasite that causes a dangerous zoonosis, alveolar echinococcosis (AE). Its presence in water sources, however, has scarcely been studied heretofore. Accordingly, 222 samples of different origin including wastewater from wastewater treatment plants (WWTPs) (n = 137), slaughterhouse (n = 49) as well as water from rivers (n = 26) and a cattle farm (n = 10) were collected from Xining City and a rural area in Qinghai-Tibet Plateau (QTP), an endemic area. Material obtained after processing of 10 L volume samples was subsequently analysed using three molecular detection methods: nested PCR, real-time PCR and LAMP. E. multilocularis DNA was found in 13 (5.85%) water samples; including 8 (5.8%), 3 (6%), 2 (20%) and 0 positive samples found in WWTPs, a slaughterhouse, a cattle farm and rivers, respectively. All three (LAMP, PCR, RT-PCR) molecular tools displayed high agreement and effectiveness in their ability of detecting the parasite's DNA in environmental material. This is the first investigation describing E. multilocularis detection in wastewater samples, using three sensitive molecular diagnostic tools. Results indicate the role of wastewater in dissemination of E. multilocularis and the risk of contamination of water sources.


Asunto(s)
Agua Potable , Echinococcus multilocularis , Animales , Bovinos , China , Heces , Tibet , Aguas Residuales
14.
J Photochem Photobiol B ; 202: 111699, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31756585

RESUMEN

In this work, we propose a novel application of ERIC-PCR technique to study DNA damage after ultraviolet radiation (UV) and peracetic acid (PAA) treatment for water disinfection purpose. The efficacy of both treatments on E. coli suspension was evaluated by two approaches: through monitoring of inactivation by conventional culture technique, and by analyzing DNA damage with ERIC-PCR. All the experiments were carried out in a batch reactor, using three intensities of UV-C radiation (10.5, 4.2 and 2.1 mW/cm2) and different PAA concentrations (4 to 16 ppm). Both treatments produced bacterial inactivation in a dose-response fashion. Based on the results of bacterial count we obtained an index of inactivation (INACI). For each sample, DNA extraction was performed and evaluated by ERIC-PCR. Qualitative modifications were observed in ERIC-PCR band patterns for all the UV-C radiation intensities used, but no changes were detected at any of the PAA concentrations. The banding pattern modifications observed are consequence of the interruption of Taq polymerase enzyme amplification-activity, caused by the presence of alterations on the DNA structure (dimer and hydrates formation). Furthermore, an index was proposed to measure DNA damage (DNADI) regarding the changes in the relative optical density values of the amplification products. A linear correlation was obtained with a high correspondence between the inactivation index (INACI) and the DNA damage index (DNADI), that was expressed as DNADI = 0.05881×INACI. This approach proves that ERIC-PCR is a feasible and valuable tool for detecting and quantifying DNA damage and it may provide a useful strategy for bacterial identification, tracking changes in DNA and providing reliable and reproducible data.


Asunto(s)
Daño del ADN , Enterobacteriaceae/genética , Purificación del Agua/métodos , Daño del ADN/efectos de los fármacos , Daño del ADN/efectos de la radiación , ADN Bacteriano/química , ADN Bacteriano/metabolismo , Desinfección/métodos , Ácido Peracético/farmacología , Reacción en Cadena de la Polimerasa , Rayos Ultravioleta
15.
Water Res ; 170: 115296, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31760361

RESUMEN

Increased frequency and severity of extreme weather events (i.e., floods and droughts) combined with higher temperatures can threaten surface water quality and downstream drinking water production. This study characterized the effects of extreme weather events on dissolved organic matter (DOM) washout from watershed soils and the corresponding contribution to disinfection by-product (DBP) precursors under simulated weather conditions. A laboratory simulation was performed to assess the effects of temperature, drought, rainfall intensity, sea level rise, and acid deposition on the amount of DOM released from soil samples. DBP formation potentials (DBPFPs) were obtained to assess the effect of extreme weather events on DBP formation and drinking water quality. The results demonstrated that the dissolved organic carbon (DOC) and carbonaceous DBP levels increased with increasing temperature in a dry (drought) scenario. Regardless of the watershed from which a soil sample was obtained and the incubation temperature during rewetting or chlorination processes, the DOC and carbonaceous DBP levels also increased with increasing temperature. Brominated DBP formation was increased when bromide was present during the rewetting of soil, indicating the effect of sea level rise. When bromide was present during the chlorination of water for DBPFP tests, only the level of brominated DBPs increased. Acid deposition had various effects under different weather conditions. The results of heavy rainfall simulations suggested that water quality deteriorates at the beginning of an extreme rainfall event. Abundant DOM was washed out of soil, leading to a peak in the DBPFP level. The level of DOM in seepage water was less than that of the surface runoff water during rainfall. The situation was more severe when the rainfall came after a long drought and the drought-rewetting cycle effect occurred.


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Desinfección , Trihalometanos , Calidad del Agua
16.
Bioresour Technol ; 297: 122395, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31761630

RESUMEN

The economic feasibility of combining forward osmosis (FO), reverse osmosis (RO) and anaerobic membrane bioreactor (AnMBR) technologies for municipal wastewater treatment with energy and water production was analysed. FO was used to pre-concentrate the AnMBR influent, RO for draw solution regeneration and water production, and AnMBR for wastewater treatment and energy production. The minimum wastewater treatment cost was estimated at 0.81 € m-3, achieved when limiting the FO recovery to 50% in a closed-loop scheme. However, the cost increased to 1.01 and 1.27 € m-3 for FO recoveries of 80% and 90%, respectively. The fresh water production cost was estimated at 0.80 and 1.16 € m-3 for an open-loop scheme maximising water production and a closed-loop scheme, respectively. The low FO membrane fluxes were identified as a limiting factor and a sensitivity analysis revealed that FO membrane fluxes of 10 LMH would significantly improve the competitiveness of FO-RO + AnMBR technology.


Asunto(s)
Aguas Residuales , Purificación del Agua , Anaerobiosis , Reactores Biológicos , Membranas Artificiales , Ósmosis , Agua
17.
Water Res ; 170: 115352, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31812816

RESUMEN

The impacts of salt accumulation, through adjusting the solid retention time (SRT), in the bioreactor on the bioprocess as well as membrane performance of a high retention nanofiltration membrane bioreactor (NF-MBR) and subsequent reverse osmosis (RO) process for water reclamation are addressed in this study. The build-up of salts (i.e., Ca, Mg, PO4) is a function of SRT, hydraulic retention time (HRT) and membrane rejection. Despite the accumulation of salts, both NF-MBRs at SRT of 30 and 60 days, achieved (i) similar biodegradation efficiency; (ii) excellent organic removal (> 97%); and (iii) excellent ammonia removal (> 98%). Extending the SRT could improve the microbial bio-flocculation capability, but did not influence the microbial activity, viability, and community structure. However, more severe membrane fouling was observed in the NF-MBR with elevated salt levels, which was attributed to the greater formation of calcium phosphate scale and Ca-polysaccharides complex (i.e., irreversible fouling layer) as well as the cake-enhanced-osmotic-pressure (CEOP) effect. Although both NF-MBRs produced comparable quality of permeate, a higher RO membrane fouling rate was observed when the permeate of NF-MBR with SRT at 60 days was fed to the RO system, implying organic compositions in NF-MBR permeate may influence RO performance.


Asunto(s)
Purificación del Agua , Agua , Reactores Biológicos , Membranas Artificiales , Ósmosis
18.
Water Res ; 170: 115361, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31816568

RESUMEN

Phosphorus removal is an important issue in the field of water and wastewater treatment. In this study, a starch-based flocculant (St-CTA), as an assisting agent, was fed after the application of traditional inorganic precipitant of ferric chloride (FeCl3) to remove inorganic and organic phosphorus from their respective simulated turbid wastewaters. The effects of various influencing factors, including CTA content of St-CTA, dosage, initial pH, initial turbidity, and initial total phosphorus (TP), were investigated systematically. This modified chemical sedimentation process assisted by St-CTA not only showed high efficient in removing TP and turbidity but also evidently reduced the required dosage of FeCl3. This combination exhibited better efficiency in removing organic TP than in removing inorganic TP from water. The synergistic mechanisms of FeCl3 and St-CTA were discussed in detail by combination of apparent removal effects and floc properties. St-CTA exhibits strong charge neutralization and bridging flocculation effects and can thus efficiently aggregate and precipitate various phosphorus and iron complexes previously formed through chemical sedimentation, adsorption, and chelation. Besides, the validation of this combination usage was further confirmed by treating a real wastewater, and half of the required FeCl3 dosage and one third of the total cost were saved after addition of only 0.4 mg/L St-CTA when 90% TP and 95% turbidity were reduced. This study thus provided a novel technique for the diminution of TP and turbidity in turbid wastewater, considerable reduction of FeCl3 dosage and final cost, and lowering of secondary pollution risk.


Asunto(s)
Fósforo , Purificación del Agua , Floculación , Almidón , Agua
19.
Water Res ; 169: 115209, 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-31669904

RESUMEN

Lead contamination in municipal drinking water is a national public health issue and is generally the result of water contact with leaded distribution piping and on premise plumbing. As a result, the US Environmental Protection Agency's Lead and Copper Rule requires point of use sampling methods at a small fraction of consumer taps on the public water distribution system. While this approach is practical, it leaves large gaps of consumers without direct monitoring and protection. In response, a novel contest-based crowdsourcing study was conducted to engage the public in monitoring their own water quality at their home taps and study factors that shaped participation in drinking water monitoring. Participants were asked to collect samples of their household drinking water through social media postings, kiosks, and community events with the chance to win a cash prize. The project distributed approximately 800 sampling packets and received 147 packets from participants of which 93% had at least partially completed surveys. On average, private wells were found to have higher lead levels than the public water supply, and the higher lead levels were not attributed to older building age. There is also no statistical relevance between the participants' perceived and actual tap water quality. Survey responses indicated that citizens were motivated to participate in the project due to concerns about their own health and/or the health of their families. In contrast, participants reported that they were not motivated by the cash prize. This project helps inform future public engagement with water quality monitoring, create new knowledge about the influence of personal motivations for participation, and provide recommendations to help increase awareness of water quality issues.


Asunto(s)
Colaboración de las Masas , Agua Potable , Monitoreo del Ambiente , Plomo , Salud Pública , Calidad del Agua , Abastecimiento de Agua
20.
Water Res ; 169: 115178, 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-31670085

RESUMEN

Pilot testing of direct potable reuse (DPR) using multi-stage ozone and biological filtration as an alternative treatment train without reverse osmosis (RO) was investigated. This study examined four blending ratios of advanced treated reclaimed water from the F. Wayne Hill Water Resources Center (FWH WRC) in Gwinnett County, Georgia, combined with the existing drinking water treatment plant raw water supply, Lake Lanier, for potable water production. Baseline testing with 100 percent (%) Lake Lanier water was initially conducted; followed by testing blends of 15, 25, 50, and 100% reclaimed water from FWH WRC. Finished water quality from the DPR pilot was compared to drinking water standards, and emerging microbial and chemical contaminants were also evaluated. Results were benchmarked against a parallel indirect potable reuse (IPR) pilot receiving 100% of the raw water from Lake Lanier. Finished water quality from the DPR pilot at the 15% blend complied with the United States primary and secondary maximum contaminant levels (MCLs and SMCLs, respectively). However, exceedances of one or more MCLs or SMCLs were observed at higher blends. Importantly, reclaimed water from FWH WRC was of equal or better quality for all microbiological targets tested compared to Lake Lanier, indicating that a DPR scenario could lower acute risks from microbial pathogens compared to current practices. Finished water from the DPR pilot had no detections of microorganisms, even at the 100% FWH WRC effluent blend. Microbiological targets tested included heterotrophic plate counts, total and fecal coliforms, Escherichia coli, somatic and male-specific coliphage, Clostridium perfringens, Enterococci, Legionella, Cryptosporidium, and Giardia. There were water quality challenges, primarily associated with nitrate originating from incomplete denitrification and bromate formation from ozonation at the FWH WRC. These challenges highlight the importance of upstream process monitoring and control at the advanced wastewater treatment facility if DPR is considered. This research demonstrated that ozone with biological filtration could achieve potable water quality criteria, without the use of RO, in cases where nitrate is below the MCL of 10 mg nitrogen per liter and total dissolved solids are below the SMCL of 500 mg per liter.


Asunto(s)
Criptosporidiosis , Cryptosporidium , Agua Potable , Ozono , Contaminantes Químicos del Agua , Purificación del Agua , Animales , Georgia , Ósmosis , Aguas Residuales
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